Telephone system.



A. h. DYSON.

TELEPHONE SYSTEM.

APPLICATION FILED MAR. 14. 1917.

Patented Dec. 31, 1918.

A. H. DYSON.

TELEPHONE SYSTEM.

APPLICATION FILED MAR. I4. 1911.

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APPLICATION FILED MAR. 14. 1917.

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A. H. DYSON.

TELEPHONE SYSTEM.

APPLICATION FILED MAR. 14. 1917 I l gggfigg Patented Dec. 01, 1918.

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orrrcn ALFRED H. DYSON, 0F MONTCLAIR, NEW JERSEY, ASSIGNOB TOKELLOGGSWITCHBOARD & SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent. Patented Dec. 31 19 18.

Application filed March 14, 1917. Serial No. 154,661.

To all whom it may concern:

Be it known that I, ALFRED H. DYsoN,

a citizen of the United States of America, residing in Montclair, county of Essex, and State of New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a'specification.

My invention relates to telephone systems and more particularly to systems in which pay station devices are provided of a type requiring the subscriber to deposit a coin or token infthe pay station associated with his instrument in order to place his substation in position to make a call. I provide means by which the coin or token is returned to the subscriber in case a connection is not obtained and means by which the coin or token is deposited in a receptacle at the substation in case a connection is obtained.

The object of my invention is to secure a superior arrangement to the arrangements of this general nature heretofore known in the art. I accomplish this ob]ect by reversing the flow of current over the calling line when the called party answers to actuate,

mechanism to collect the suspended coin. This reversal of current may also be used for supervisory purposes.

In accordance with my invention, I provide an arrangement at the subscribers station requiring the subscriber to deposit a coin before sending in his call. In case a connection is obtained, the answering subscriber by his act of answering the. call, ordinarily by the removal of his telephone from its hook, reverses the current over the calling line-thus actuating mechanism which deposits the coin in the receptacle provided for it. In case a connection is not obtained the calling subscriber, by placing his telephone upon its hook, causes the coin to be returned to himself.

The present application is a continuation 'w1per A", shown in the illustration.

nected to an automatic switch with which is shown associated the circuits of a first selector.

Fig. 3 illustrates similarly the circuits of a second selector and a battery control circuit.

' Fig. 4 illustrates similarly the circuits of aconnector and a second telephone line pro vided with its automatic switch.

Fig. 5'illustrates circuits of a second selector and a battery control circuit different from that of Fig. 3.

Fig. 6 illustrates a trunk circuit and a battery control circuit adapted to be used in trunking between exchanges.

Fig. 7 illustrates a substation equipped with pay station apparatus.

Referring first to Fig. 1, the switch there shown is adapted to be operated by means of escapement movements; shaft 1, when the switch is in its idle or normal position, having a tendency to revolve, due to its being attached to motor-spring 37. Upon the lower portion of shaft 1 are rigidly mounted thirty wipers in sets of three, A", AKA, etc; B", B etcf; C G etc.; those having the same co-efficient constituting a set. These wipers are insulated from each other and are disposed radially by sets, with being provided with a common strip extending beneath and parallel to it. The said contacts are mounted in threebanks in vertical and horizontally curved rows.

A top view of the wipers and contact banks is shown in Fig. 1, a. being the com mon terminal. When shaft 1 is caused to rotate from left to right, wiper A passes over the horizontal curved row of contacts a. When the said wiper has revolved a distance such that it assumes the positionof wiper A", as shown in Fig. 1, wiper A is in a position, with respect to the verticaledge of the contact bank, similar to that of The shaft continuing to revolve, wiper A passes over the lowest curved row ofcontact points al When the said Wiper has passed over the last of said contact points, the shaft continuing to revolve, wiper A engages the first contact at the left of row (1 and when the said wiper has left the row, wiper A begins passing over the contacts of its appropriate rOW. It will be seen that one complete revolution of the shaft 1 will. cause each immovable contact of a bank to be wiped by its appropriate wiper. Wipers B", B etc., C", G etc., operate co-inci-v dently with wipers A", A, etc., with respect to'their appropriate contact banks.

In accordance with my invention, in operating the switch, a number of primary rotary movements of the shaft are allowed, depending upon the level of immovable contacts with which it is desired to connect. Each of these first movements is sufficient to move a set of wipers entirely across its respective rows of contacts. When the desired set of wipers is, in this manner,

brought, with respect to its contact banks,

to a position corresponding to that of wiper v A", as shown in Fig. 1, a .number of secondary rotary movements of the shaft in the same direction are allowed, to move the revolution upon which it has been started, 1

said desired set of wipers, from contact to contact of its rows, each movement causing. the wipers to close contact between successive contacts'and their commons, the movement of the wipers being arrested when the proper contacts are engaged by them.

To secure the return of the switchto normal, the shaft is allowed to complete the its movement being arrestedas soon as the revolution is completed. Upon such completion, apparatus is automatically brought into play to cause spring 37 to be wound up, preparatory for a further'use of the switch. It will be noted that each time the switch is operated and returned to normal,

each contact in the different banks is wiped by its appropriate wiper, and this is believed to be a new and valuable feature of switch of this character, inasmuch as the accumulation of dust. upon contacts and wipers is prevented and they, themselves, kept, at all times, bright and clean.

The movements of the shaft are controlled in the following manner, reference being had to Fig. 1: One or more impulses of current are first caused to flow through magnet 8, depending upon the contact levels to be selected. Each impulse of current causes the attraction and release of armature 9. Mounted upon shaft 1 is a disk l, having [a single tooth in its periphery which,- as 55 shown in the illustration, is engaged by detent 15, preventing the movement of the shaft. Arm 10 mounted upon armature 9 (the end of'which isillustrated as broken) extends downward so as to overlap arm 14 mounted upon armature 12, its lower end being on a level with the lower end of arm 14, this being shown complete in Fig.

1. The first attraction'of armature 9 causes arm 10 to press against the pro e ct1on shown upon detent 15, causing the said detent to ture 9 permit movements as described, and

the extent of these movements is so gaged as to bring successive sets of wipers to positions in front of, but not engaging, the first contacts of their respective levels.

Fig. 1 is, a top view of ratchet wheel 2, detent 5- being shown in the normal position.

3 is a second ratchet wheel rigidly at-,

tached to shaft 1, its teeth being so spaced that successlve movements as determined thereby, allows movements of the wipers from contact to contact only. Normally engaging the saidratchet wheel 3, is detent 7-, having upon it a projection adapted to .be engaged by arm 10 upon armature 9 with each attraction of the said armature, and moved out of engagement with ratchet wheel 3 and so held as long as the armature is attracted. With each release of armature 9, detent 7 engages a tooth of wheel '3 and arrests rotation of the shaft.

The rows having been selected in the man ner described, one or more impulses of current are now caused to flow through magnet 11, depending upon the proper contacts in the rows. Each impulse causes the attraction and release of armature 12 which controls detent 6 in a manner generally similar to that in which detent 5 is controlled by magnet 8 the shaft being permitted to rotate one step for each impulse. Detent 7, with each energization of magnet 11, is caused to release ratchet wheel 3 by the operation of arm 13; and upon the deenergization of the magnet, again engages the wheel, preventing movement of shaft 1.

Fig. 1 is another view of the arrangement of these parts. Upon armature 12 of magnet 11, is shown arm 14, adapted to cause the retraction of detent 15, should the detent be in its normal position at the time magnet 11 is energized. This is necessary to enable wipers A", 13, and C to be controlled by magnet 11 in a from-contactjto-contact movement, inasmuch as a comengagement of disk 4 by detent 15.

naearoe Referring now to Fig. 1, when magnet 16 is energized, pawl 21, pivotally assoillustration upon detent ciated with its armature 20, moves downward, engaging the next tooth of ratchet wheel 26. When the magnet is deenergized, armature 20 is retracted and pawl 21 moves in a vertical direction, causing ratchet wheel 26 to revolve one step from left to right. The said ratchet wheel is rigidly attached to ratchet wheel 27, moving the latter with it, and the end of lever of engagement with the tooth of ratchet wheel 27, previously engaged by it, and rests upon the periphery of the wheel. The said lever being mechanically connected to circuit changing spring 29 as shown, this movement causes the said spring to disengage spring 28 andto engage spring 30. Lever 27 a may be mechanically attached to, and cause simultaneous movements of, a plurality of circuitchanging springs.

\Vhen magnet 22 is energized, its armature 23 is attracted. Pivotally associated with the said armature is pawl 24, engaging a tooth of ratchet wheel 26, the pawl upon the attraction of armature 23 moving toward the left, revolving ratchet wheel 26 one step and thereby moving ratchet wheel 27 into such a position that lever 2.7 again engages with its end a tooth of ratchet wheel 27, adjacent to that from engagement with which it was moved by the above-described operation of pawl 21. This operates to move the circuit changing spring 29 out of engagement with spring 30 and again into enarmature 23 also moved The attraction of manner that arm 25 toward the left in such an orifice toward its projecting end is caused to slip over and engage the pin shown in the 7. In Fig. 1", a top view of these parts is shown. When magnet 22 is deenergized, arm 25 is moved toward the right by the return of armature 23, and reference to Fig. 1 makes clear the manner in which this movement of arm 25 moves detent 7 out of engagement with ratchet wheel 3.

The disengagement of detent 7 in the manner described operates to restore the wipers to normal by allowing a free rotation of the shaft, until detent 15 engages the single tooth of disk 4.

Referring to ing it from in front) an arm of conslderable length, extending from the rear of the switch and engaging, with one edge, a disk fastened to shaft 1 at all times. When the shaft is in its normalposition, as shown in Fig. 1, the edge of arm 31 engages a depression or flattened portion 31 in the periphery of disk 31, as shown in Fig. 1, and, in this position the arm 31 engaging the projection shown upon arm 25, holds the said arm above the pin on detent 7. With 27 is moved out,

gagement with spring 28, its normal position. I

Fig. 1, 31 illustrates (v iew-.

the first rotary movement of the shaft, the edge of arm 31 disengages the depression mentioned, and rests upon the periphery of the shaft; its end, under these circumstances, being moved to the right so that it no longer supports arm 25in the posit-ion shown in Fig. 1. It is retained thus retracted until the shaft has completed one revolution. Whenthis occurs, its edge again engages the depression in shaft 1 before mentioned, its end moves forward and lifts arm 25 out of engagement with detent 7 in which it was placed to release the switch, so that the said detent again engages ratchet wheel 3. This, it will be noted, occurs at the termination of the release operation before described and simultaneously with the engagement of detent 15 with disk 4, detent 7 being thereby returned to normal andready to perform its usual function upon the next operation of the switch.

The means by which spring 37 is wound up after the return of the wipers to normal will now be described. The details of the mechanism used for this purpose are shown in detail in Fig. 1*. Attached to the upper portion of shaft 1, is cam 36 having an offset, as shown in Fig. 1 normally engaged by pawl 38. As the shaft is revolved, cam 36 gradually moves pawl 38 to the left; and when the shaft approaches the completion of its revolution, pawl 39, attached to and moving with pawl 38, engages a tooth of ratchet wheel 41 adjacent to that previously engaged by it. As soon as the revolution of the shaft is completed, pawl 38 engages the otf-set in cam 36, its free end moving toward the center of the shaft and retracting pawl 39 to move ratchet 41 one step from left to right. Ratchet 40 is rigidly attached to ratchet 41 and moves with the latter, the end of spring 43 (see Fig. 1) being moved out of its engagement with a tooth of ratchet 40, which is its normal position, in such a manner that it rests upon the periphery of the said ratchet. Spring 43 is thereby caused to engage spring 42, and this closes circuit through winding magnet 32. The said magnet is arranged in a vibratory circuit, a novel form of circuit breaker being provided consisting of disk 46 (see Fig. 1) and its associated parts. This circuit breaker is designed to secure a full stroke of the armature of magnet 32 before disk 46 is provided a depres- "edge of orifice 46 I springs 47 and 48, and causing another en- Mounted upon ratchet 34 is cam 35 1) ergization of the magnet.

Each attraction and releaseof armature 33 of magnet 32 causes ratchet 34 to be revolved a step from left to right by means of pawl 33, the said ratchet moving independently of shaft 1, and the shaft remaining motionless under these conditions. One end of spring 37 is attached to ratchet 34 and the movement of freely moving ratchet 34 is in the same direction as the movement of the shaft when the switch is operated. This movement of ratchet 34, therefore, operates to wind'up the said spring.

Fig. its shape being similar to that of cam 36, being provided with an ofi'- set normally engaged by pawl 38. The described winding movement of ratchet 34 moving cam 35 with it, gradually moves pawl 38 to the left; and when ratchet 34 approaches the completion of its revolution, pawl 38 causes pawl39 to engage the next tooth of ratchet 41. When armature 33 has been-vibrated a sufli'cient number of times to cause a complete revolution of ratchet 34, cam 35 will also have made a complete revolution and pawl 38 again engages its off-set. Pawl 39 then moves to the right and effects a rotary movement of ratchet 41 one step from left to right. It will be noted that this is the second movement of. ratchet 41 accomplished in the winding operation, and this second movement operates to bring ratchet 40 in such a position that spring 43 moves from the periphery of the ratchet into engagement with the tooth next to that engaged by it before the wind- 1ng operation commenced. This engagement be causes spring 43 to disengage spring 42 and opens the circuit of magnet 32, preventing further operation of the said magnet.

11 operating parts of the switch have now been returned to normal, and energy has been stored for operating the switch a second time.

While I have especially designed the switch, shown in Fig. 1, for use in connection with the circuit arrangements shown at the right of. Fig. 2, at the left of Fig. 3, at the left of Fig. 5, at the right of Fig. 6, and.

with minor changes in connection with the circuit arrangement shown at the left of Fig.

terminals of first contacts may conveniently 'be disposed in one above the other;

4, the invention of the latter figures is not necessarily confined to the operation of such a machine as I show in Fig. 1. Fig. 1 is generically illustrative of forms of mechanical movements which different parts of the circuit arrangements, comprised in my invention, may assume. For purposes of reference, I shall designate, .by descriptive terms, the principal magnets illustrated in Fig. 1. When, inthe description of the circuit drawings, I come to an electromagnet whose work may assume a form similar to that accomplished 'by a magnet of Fig. 1, I shall designate it by the descriptive title.

A magnet, having functions similar to megnet 8, may be called a primary magne A magnet, having functions similar to magnet 11, may be referred to as a secondary magnet.

magnet, having functions similar to magnet 16, may be referred to as a circuitchanging switch magnet.

' magnet, having functions similar to magnet 22, may be referred to as a release magnet.

Referring to the circuit arrangements, Figs. 2, 3 and 4 placed in the order named with Fig. 2 at the left constitute a first complete diagram illustrative of the circuits of the telephone system of my invention. The

apparatus included in this single diagram is that necessary for establishing connection between two subscribers lines. In Fig. 2, I have illustrated a substation A, including a pair of keys 60 and 61 adapted to be used by the subscriber for'grounding limbs P and S, respectively, of the telephone line at will. A key 62 is also provided, enabling the subscriber to open the metallic circuit of the substation. Limbs P and S extend to the central oiiice and are there connected with an automatic switch individual to the line,

which may be called a private switch.

The system, which I have shown in the diagram referred to, may be used to accommodate several thousand subscribers. Each subscribers line is providedwith an automa-tic switch, having circuits similar to those illustrated in Fig. 2, and these switches may conveniently divided into groups of one hundred, each switch including movable switch arms or wipers such as are designated 82, 98 and 97 in Fig. 2, together with a plurality of contacts constituting the multipled selector switches. These three curved rows, those of the upper row, among which contact 80 would be included, being disposed in such a manner that successive terminal contacts alternate with permanently grounded contacts, such as contact 81. Each row or level of contacts is provided with a common strip, such as I have shown at 79, 100 and 99 in Fig. 2. These common strips are the true terminals of the circuits'of the private switch, wipers 82, 98 and 97 having themselves no circuit connections, but being arranged so that when the switch is operated,

they close circuits. between the common strips and the contacts before mentioned.

The number of first selector switches, assigned to a group of one hundred private switches, may vary, depending upon the number of calls which may be expected to co-exist from the lines of the group. Ten first selector switches for a group of one hundred private switches would be suflicient in an ordinarily busy exchange.

A first selector switch, circuits of which I have illustrated at the right of Fig. 2, is common for connection to all subscribers in the exchange.

At the left of Fig. 3, I have illustrated the circuits of a second selector switch, such a switch being common for connection to a group of one thousand subscribers lines;

At 'the left of Fig, 4, I have illustrated the circuits of a connector switch, such a switch being common for connection to a group of one hundred subscribers lines.

Generally. speaking, a calling subscriber first connects his telephone line through to a first selector switch by operating his private switch. He thereupon operates the first selector switch in such manner that it connects his line through to a second selector switch assigned to the one thousand line group of subscribers lines, among which is included the line of the subscriber whom he is calling. The subscriber then operates the second selector switch in such manner that it connects his line through to a connector switch adapted to be operated to connect his line directly to any line of a one hundred line group of the aforementioned one thousand line group, among which is the line of the desired subscriber. He then operates the connector switch to connect his line through to the desired subscribers line. The system operates as a multiple trunk system, the principles of which are well known in the art. Referring to the complete diagram before mentioned, and assuming that subscriber A desires to connect his line with the line of subscriber B, whose number is assumed to be 3456, the operation of the system is as follows: Subscriber A first removes the receiver from the switch hook, closing contact 737 2 and establishing a flow of current as follows: from ground at the central office, through contact 6768, through contact 6970, over limb S of the line, returning over limb P, through contact 63-64.. through the winding of relay 66 to battery 74, energizing relay 66, which attracts its armatures. This attraction causes a flow of current from ground, through contact 86- 87, through contact 7675, through the winding of magnet 90, contact 9192, to battery 74. Magnet 90 is placed in a vibratory circuit and will alternately be ener gized and deenergized as long as relay 66 is maintained energized, due to contact 7 6- being closed. Each energization and deenergization of magnet 90 causes shaft 96 to rotate a step, carrying with it rigidly attached wipers 82, 98 and 97. The first movement of the shaft brings wiper 82 out of engagement with a contact, a multipled terminal of the first selector switch last used by subscriber A'in establishing a connection, and into engagement with a permanently grounded contact such as 81. Ourrent thereupon flows from ground, through ground, through relay 89 of the private switch then connected with a multipled terminal of the first selector switch, through contact 83 of the said private switch, through the common strip of the said switch, its wiper 82, a contact, a multiple of the one which wiper 82 of the private switch of subscriber A just engaged, through the contact engaged by the said wiper to the common strip of the private switch of subscriber A, through contact 8384 of the said switch, through contact 7778, through the winding of relay 66 to battery 74. The windings of relays 66 and 89 are so proportioned that this flow of current is not of sufficient volume to cause relay 89 to attract its armature. A third energization and deenergization of magnet 90 again brings wiper 82 into engagement with a permanently grounded contact, and a fourth energization and (le'energization of the said magnet brings wiper 82 again into engagement with a contact, a terminal of a first selector switch. Assuming that the contact thus engaged is contact 80 of the first selector switch illustratedin Fig. 2. and that the said switch is idle, circuit through relay 66 is broken. due to the fact that contact 80 is insulated from ground. as appears upon an inspection of Fig. 2, in which the first selector switch is shown in its idle position. Relay 66 becomes deenergized, the retraction of its armature opening the circuit of magnet 90 at contact 7 67 5, thereby arresting wipers 82, .98 and 97 in engagement with contacts 80, 100 and 99, respectively.

When relay 66 wasfirst energized, it prepared for the movement of arms 83, 246,- 63 and 70 into engagement, respectively,

' with contact points 85, 246, 65 and 71; and

upon its de'e'nergization, caused the engagement of the said arms with the said contact points. A reference to magnet 16, illus- 10 trated in Fig. 1, and the method of operation of the said magnet in connection with ratchet 27, discloses a convenient mechanical combination by which the' aforesaid movement may be effected.

The engagement of contact-point 85' by arm'83'p'ut ground on contact 80 of the first selector switch and its multiples, through relay 89, rendering the said switch busy with respect to other private switches having ac cess to it. The engagement of arm 246 with contact point 246* rendered the private ing of primary ma switch of subscriber A busy vwith respect to other subscribers establishing connection with his line; The engagement of arms 63' and with contact points 65 and 71, re-

spectively, extended the limbs ofthe line of subscriber A through to the circuits of the first selector switch, thereby rendering the said switch controllable by subscriber A from the substation.

Subscriber A, by means of key 60, now

grounds lim=b P of the line a number. of

times,'corresponding to the thousands digit of the called subscribers number, or three of current to flow from ground at the first selector switch, through contact 108-109, through contact 106105, through the windgnet 114 to battery 74. The resulting energizations of the primary 'magnet 114. causes three primary rotary movements of shaft 132. The third movement brings wipers 129, 133 and 136 to positions ad acent to, but not engaging, the first contacts of three horizontal rows of contacts, multipled terminals of second selector switches assigned to the third one thousand line group of subscribers lines, or

a group including lines of subscribers to whom are assigned numbers from 3,000 to 3 999.

Subscriber A now sends, by key 61, one

impulse of curre'nt'from ground at the substation, over limb S of the telephone line, through contact 70-71, through contact nals of a second selector switch already in lector switch, through its contact 128126,

through contact 115-116, through the winding of secondary relay 118 'to battery 74, 'causin a single attraction and release of the re ays armature and a flow of current from ground, through contact 119'120, through the winding of circuit-changing switch magnet 111 to battery 74. This causes the energization of the said magnet and the attraction of its armatures. The attraction of armature 108 causes a flow 75 of current from gr'ound, throughcontact 1081l0, through the winding of secondary magnet 122 to battery 74. The latter magnet is arran'ged in a vibratory circuit. Its first energizationj and deenergization oper-. ates to move wipers 129, 133 and 136 intoengagement with the first contacts of the rows described. In case these are termi-- use, circuit-changing'switch magnet 111 is maintained energized by a flow of current from ground at thev first selector switch then connected with the said second selector switch, through relay 139 of said first sethrough its common strip 131; itswiper 129,

a multiple of the contact engaged, to the said contact, through wiper 129 of first selector switch, Fig. 2, to common strip 131,through contact 126.127, through contact 113112,

through the winding of magnet 111, to bats tery 74. The windings-of relay 139 and 111 are so proportioned that this flow of current is not of sufficient volume to cause relay 139 to attract its armature. It is ap-' parent that secondary magnet 122 will continue to vibrate, causing with each energization and deenergization a secondary movement of shaft 132, carrying with it wipers 129, 133 and 136 as long as magnet lll continues energized. When wipers 129,

133 and 136 engage contacts, terminals of an idle second selector switch, which is as- 'sumed to occur when they engage contacts 130, 134 and137, terminals of second se- 1'10' lector switch, 3, contact 130 isinsulated from ground and the flow of current through magnet 111 is interrupted. Its armatures thereupon resume their normal positions shown in the il'lustration,breaking contact 115 108-110' and preventing further operation of-secondary magnet 122. Wipers 129, 133 and 136 are thus brought to rest in engagement with contacts 130,134 and 137. The deenergization of circuit-changing switch magnet 111 also moved arms 126, 102 and 115, respectively, into engagement with contacts 128, 103 and 117, respectively. The closure pf contact 126 -128 put ground through 28- 130, rendering the second selector switch busy with respect. to other first selector switches having access to it. The closing of contacts 101103 and 115117 extended 13o iota- 139, through contact 128l26, contact 131129-130, to the multiples of contact of current to flow from ground at the substation, over limb P, through contact 142-143 of second selector switch, Fig. 3, through the winding of primary relay 145 to battery 149. These impulses cause the armature of the said relay to be attracted and released four times and four impulses of current to flow from ground at the second selector switch, through contact 150-151,

- the winding of circuit-changing switch mag through contact 148-147, through the Winding of primary magnet 153 to battery 149. Each impulse through magnet 153 causes a primary movement of shaft 168, carrying with it wipers 165, 169 and 172. The fourth of these movements brings the wipers to po sitioris adjacent to, but not engaging, rows of contacts, multipled terminalsof connector switches assigned to a group of lines including subscribers lines which are assigned numbers from 400 to 499 of the selected one thousand. I

Subscriber A now causes a single impulse of current'to'flow from ground at the substation, over limb S of the line, through contact 204-205 of the second selector switch,

through secondary relay 207 to battery 149, causing a single attraction and release of the relays armature,-and an impulse of current to flow from ground at the second selector switch, through contact 210-209, through net 154 to battery 149. The consequent attraction of the magnets -armatures established a flow of current from ground, through contact 150-152, through the winding of secondary magnet 157 to battery 149. Magnet 157 is placed in a vibratory circuit and will alternately be energized and deinergized until contact 150-152 is broken. Each energiza tion and denergization of magnet 157 causes a secondary rotary movement of shaft 168, moving wipers 165, 169

and 172 to successive sets of contacts, terminals of connector switches of the described group, until terminals of an idle switch are reached. In case contacts of the rows, engaged by wipers 165, 169 and 172, are terminals of a busy connector switch, magnet 154 is maintained energized by fiowof current from ground at the second selector switch then connected with the said connector switch, through relay 175, contact 162-164, contact 167-165 of the second selec'tor switch referred to, to a multiple ofthe contact engaged by wiper 165 01"" Fig. to said contact, to common strip 167 of the second selector switch now being operated,

through its contact 162-163, through contact 156-155through the winding of magnet 154 to battery 149. Such flow of current is of insufficient volume to cause relay 175 to attract its armature. When a contact terminal of an idle connector switch is.

reached by wiper 165, such contact will be insulated from ground and circuit through magnet 154 will be interrupted, deenergizing it and thereby allowing the return of its armature to normal and preventing further energizations and denergizations of secondary magnet 157; wipers 165, 169 and 172 resting in engagement, respectively, with contacts 166, 170 and 173, assumed to be terminals of a trunk line extending to the selected connector switch shown in Fig. 4. The deenergization of circuitchanging switch magnet 154, above mentioned, also caused arms 162, 142 and 204 to move into engagement with contacts 164, 144 and 206, respectively. The closing of contact 162-164 put ground to contact 166 and its multiples, rendering the said connector switch busy with respect to other second selector switches having access to it. The closing of contact 142-144 and contact 204-206 extended'limbs P and S of the telephone line of subscriber A through to the circuits of the connector switch shown in Fig. 4, rendering the said switch controllable from substation A.

Subscriber A now causesfive impulses to flow from ground at the substation, through contact 171-169-170, contact 178-179,

contact 181-182, contact 184-185, and through the winding of primary relay 188 of the connector switch. Five attractions and releases of said relays armature are caused thereby, resulting in five impulses of current a primary rotary movement of shaft 239,

carrying with it wipers 236, 240 and 243. The fifth movement brings the wipers adj acent to rows of contacts, multipled terminals of the lines of subscribers'to whom are assigned numbers from 3451 to 3460.

Subscriber A now sends one impulse of current from ground at the substation, through contact 17 4-17 2-173, through contact 211-212, contact 216-214, contact 217-218, through the winding of relay 221 to battery 189. The resulting attraction and release of the relays armature causes an impulse of current from ground through contact 192-223, through the winding of circuit-changing switch magnet 193 to bat tery 189. The resulting energization and denergization of magnet 193 operates to move arms 224, 198, 184, 217 and 228 into engagement with contacts 226, 200, 186, 219 and 230, respectively. The engagement of arm 198 with contact 200 places secondary magnet 233 under control of primary relay 188. Six impulses of current are -now caused by subscriber A to flow from ground at the substation, through contact 184-186 and primary relay 188, Fig. 4, to battery 189. Each of the six attractions and releases of the relays armature causes a flow of current from ground, through contact 192-191, through contact 195194,'through contact 198-200, through the winding of secondary magnet 233 to battery 203. Each energization and denergization of the said seco ndary magnet causes wipers 236, 240 and 243 to move to engage successive contacts of the rows above-mentioned, the sixth movement bringing the wipers into engagement, respectively, with contacts 237, 241

and 244, multipled terminals connected to the private switch of subscriber B, or subscriber 3456. Subscriber A now causes one:

the connector switch, through relay221 to battery 189, causing circuit-changin switch magnet 193 to be energized by esta lishing a flow of current over the path previously traced.

Assuming first that the line of the called subscriber is busy, contact 237 in this case is characterized by a ground connection; and upon the attraction of armature 196 of magnet 193, closing contact 196-197, a flow of current results from grounded contact.

237, through wiper 236, through common strip 238, through contact 224-226, contact 197-196, through the winding of release magnet 232 to battery 189, energizing magnet 232. When the impulse through relay .221 ceases, causing the deenergization of circuit-changing switch magnet 193, the lat ters armature 196 disen ages anvil 197, opening circuit through re ease magnet 232, causing its deinergization and the consequent return of the connector switch to normal; wipers 236, 240 and 243 disengaging contacts 237, 241 and 244, and arms 224, 198, etc., returning to their normal engagement with contacts 225, 199, etc.

When the connector switch returns to normal, contact 235-234 is closed and the calling subscriber receives the busy signal from machine 263 in his receiver, notifying him that the line called is busy. He thereupon simultaneously presses keys 60 and 61 and replaces his receiver. Relays 188' and 221 of the connector switch, Fig. 4, are simultaneously energized-closing contact 190-222, establishing a path for the flow of current as follows: from ground at second selector switch. Fig. 3, through release relay 175, through contact 164-162, through contact 167-165-166, through contact 251-250 (Fig. 3) through contact 190-222 (Fig. 4)

ates to prepare the second selector switch,

Fig. 3, first selector switch, Fig. 2, and private switch, Fig. 2, for thelr returns to normal, Whichwill occur as soon as subscriber A releases keys 60 and 61, thereby removing ground from the limbs of the line, which causes the deenergization of relays 188 and 221 of Fig. 4, and the opening of contact 222-190. The opening of this contact causes the de'nergization of release relay 175. The detailed description of the manner-in'which release relay 175 operates in connection with the returns .to normal of the various switches will be hereinafter given. I

In case the line of subscriber contact 237 is connected to battery through V relay 266, and-release magnet 232 does not become energized upon the closure of contact 196-197. In this case, the energization and denergization of circuit changing switchmagnet 193 operates to move arms 224, 198,

B is idle,-

184, 217 52nd 228 into engagement, respectively, with contacts 227, 201, 187, 220 and 231. tact 227 places ground upon contact 237 and its multiples, rendering the said line of subscriber B busy with respect to other subscribers establishing connection with it. It also energizes relay 266 of the private switch which operates to cut limbs P and S of the line of subscriber B free from the circuits of the private switch. The engagement of arm 228 with contact point 231 establishes a path for the flow of current as follows from ground at battery control circuit, Fig. 3, through the windin contact 231-228 0 the connector switch, through the winding of release magnet 232 to battery 189, causing the energization of relay'247. The windings of magnet 232 and relay 247 are so proportioned that this flow of. current does not cause the energization of magnet 232 to a degree to cause it to attract its armature. It will be observed that the structure of Fig. 1 does not provide for a The engagement of arm 224 with conof relay 247, through.

second forward movement of circuit-chang- I 193 controlling the forward stepping of the side switch arms, while release magnet 232 when decnergized, restores the side switch arms, all as described in the patent cited.

The energization of relay 247 operates to close the following contacts: 178-180, 182- 183, 211-213 and 214-215. A flow of ourrent'now results over the followingpath: from the grounded side of battery 256, through the lower winding, as illustrated, of relay 255, through relay 252, energizing the said relay and attracting its armature through contact 213-211, through contact 17 3-172-17 4, over the talking circuit as shown by the heavy lines, by way of limb of the line of subscriber A, through the substation, supplying current to the transmitter for talking purposes, returning over limb P, the other side of the talking circuit through the exchange, through contact 171-169- 170, contact 17 8-180, impedance coil 263, through the upper winding of relay 255, to the active side of battery 256. This flow of current does not cause relay 255 to ttract its armature, the said relay being difierentially wound.

To cause the bell of subscriber B to be rung, subscriber A opens the path of the just-traced flow of current at his substation by means of key 62. This causes the deenergization of relay 252, its armature assumes the position shown in the illustration (Fig. 3) closing contact 253-254 and establishing a path for the flow of current from ground (Fig. 3) through contact 249-248, contact 253-254, through the Winding of ringing relay 257 to battery 256. This energizes the said relay, it attracts its armatures and cuts ringing generator 258, by the said attraction, into circuit with the line of subscriber B, causing his bell to ring. When subscriber A releases key 62, the talking current resumes its flow through the substation, relay 252 is again energized, the attraction of its armature breaking circuit through ringing relay 257, whose armature'sresume their normal positions as shown in Fig. 3.

When subscriber B answers the call by removing his receiver from the hook, contact 72-73 is closed, and a flow of current results from the grounded side of battery 256 (Fig. 3) through impedance 265, over the talking circuit at the exchange, as shown by the heavy lines, to limb S of the line of subscriber B, through the substation, supplying current to the transmitter, returning over limb P of the line, over the talking circuit, through impedance 264 to the active side of battery 256. The two subscribers are now in conversation through condensers 261 and 262, the conversational circuit being traced through the exchange by the heavily lined conductors.

When the subscribers have finished their conversation, each depresses simultaneously keys 60 and 61 and replaces his receiver upon the switch hook. Assuming that subscriber B does this first, the release of the apparatus used in establishing the connection between the twosubscribers is secured in the follow= ing manner: the grounding of limb S by tion and before did not cause the attraction of armature 259. The short circuiting of the lower winding as above described, current continuing to flow in the upper winding, causes the magnetization of the core of relay 255 and the attraction of its armature 259 to engage anvil 260. A flow of current is thereby caused over the following path: from ground, Fig. 3, through the winding of release relay 175, through contact 164-162, through contact 167-165-166, through contact 259-260, joining the current flowing from ground through relay 247, through contact 231-228, through the winding of release magnet 232 to battery 189. Relay 17 5 and magnet 232 are of low resistance and the above-described flowof current causes theattraction of the armatures of both. The ener zation of release magnet 232 prepares for t e return of the connector switch, Fig. 4, to normal upon the deenergization of the said magnet. The attraction of the armature of the release relay 175 establishes a path for the flow of current as follows: from ground, Fig. 2, through the winding of release relay 139, through contact 128-126, through contact 131-129-130, through contact 17 7 -176, through the winding of release magnet 161 to. battery 149, causing the attraction of the armatures of relay 139 and magnet 161. The attraction of the armature of magnet 161 prepares for the release of the second selector switch, Fig. 3, and its return to normal upon the denergization of the magnet. The energization of relay 139 establishes a path for the flow of current as follows: from ground at the private switch, Fig. 2, through the winding of relay 89, through contact 85-83, through contact 79-82-80, through contact 141-140, through the winding of release magnet 125 to battery 74, the resulting energization of magnet 125 preparing for the release of the first selector switch, Fig. 2, and its return to normalupon the deenergization of the said magnet. The energization of relay 89, which results from the above-described flow of current, causes a flow of current as follows: from. ground at the private switch, through contact 86-88 through the winding of relag 66 to battery 74, and theenergization of t e said relay.

When subscriber B releases keys 60 and 61, they return to their normal positions as shown; assuming that subscriber A has not 260. This causes the deenergization of release magnet232 of the connector switch, Fig. 4, and the return of the switch to normal. switch opens the circuit of relay 247 of Fig. 3. Its consequent deenergization and the release of its armatures causes arms 178, 211, 182 and 214 to return to normal. The release of the connector switch also causes relay 266 of private switch, Fig. 4, to become denergized, restoring the private switch to normal. The deenergization of release relay 175 of the second selector switch, Fig. 3, is

caused by armature 259 disengaging anvil 260. The resulting opening of contact 17 617 7 deenergizes release magnet 161, causing the return of the second selector switch to normal. energization of release relay 139 and the opening of contact 140-14l. The opening of this contact causes the deenergization of release magnet 125 and the return of the first selector switch, Fig. 2, to normal. It also causes the deenergization of relay 89 and the opening of contact 8886. The opening of this contact causes the denergization of relay66 and the return of arms 83, 246, 63 and 70 to their normal positions as shown in the illustration. It is to be understood that the release of the private switch, or its return to normal, consists in the above-described operation only, wipers 82, 98 and 97 remaining in engagement with terminals of the first selector switch used. The return of arm 83 to its normal engagement with its contact 84 removes ground from contact 80 and its multiples, rendering the first selector switch, Fig. 2, idle with respect to other private switches having access to it.

Should subscriber A depress keys 60 and 61 at his substation and replace his receiver before subscriber B does so, the grounding of limb S of the line of subscriber A short circuits the lower winding of relay 255, current continuing to flow through the upper winding, over limb P, to ground at the substation. The core of the relay is thereupon magnetized, armature 259 engages anvil 260,

and the release operations proceed exactly as described in the case in which subscriber B performs the release operation at hlS substation first. I

It will be noted that during conversation, current flows through diflerentially wound relay 255 and in parallel paths over the lilies of the two connected subscribers; that when one subscriber releases in advance of the other,'current through the upper winding of relay 255 is of equal or of greater volume than that during conversation; while current through the lower winding is reduced approximately one-half, the degree depending upon the comparative resistance 0f the t o subscribers lines.

.The return of arm 228 of this It also causes the de-.

Should the two subscribers release simultaneously, the flow of current through the upper winding of relay 255 will be substantially the same as that existing during conversation, while the fiow of current through the lower winding will be practically 10,27.

A second complete diagram, illustrative of an alternate form of the circuits of the telephone system of my invention, comprises Fig. 2, Fig. 5 and Fig. 4, placed in the order named. The method of operation of this circuit is largely the same as that of the circuit diagram already described, the diflerence existing in the battery control circuit, Fig. 5. The said Fig. 5 provides means whereby, upon the response of the called subscriber, the direction of the flow of current in the line of subscriber A is reversed.

' The description already given in connection with the previous circuit diagram ap-- plles to this second diagram to the point at contact 270271, through contact 3O1300 and through the winding of primary relay 188, operating the connector switch of Fig. 4 in the manner already described. The single impulse sent over limb S of the line after the Just mentioned set of primary impulses, after passing through contact 174 172-173, passes through contact 273-274, contact 305303 and through the winding of relay 221. The impulses corresponding to the units digit sent over limb P, and the single impulse sent over limb S thereafter, traverse the above described paths.

The release of the connector switch, in case the line of the called subscriber is busy, is secured in the same manner as described in connection with the preceding diagram. Should the line of subscriber B be idle, arms 224, 198, 184,217 and 228 are caused to engage contacts 227, 201, 187, 220 and 231, as in the preceding description. The engagement of arm 228 with contact point 231 es- Current thereupon flows as follows: from the grounded side of battery 287, through the lower winding of difierentially-wound relay 284, through the lower winding of relay 281, through contact 293-294, through contact 275-273, over the talking circuit at the exchange, to limb S of the line of subscriber A, throughthe substation, returning over limb P, over the talking circuit, through contact 270-27 2, through contact 296-295, through the upper winding of relay 281, through the upper winding of relay 284, to the active side of battery 287. The core of relay 284 is not magnetized by this flow of current, owing to its difierential windings. The core of relay 281 is energized, attracting its armature 283 to open contact 282-283. Subscriber A opens the path of the previously traced flow of current by means of key 62, causing the deenergization of relay 281, armature 283 falling back to establish a path for the flow of current as follows: from ground, through contact 282, 283, through contact 280-279, through the winding of ringing relay 288 to the active side of battery 287. Relay 288 attracts its armatures, cutting ringing generator 289 into circuit with the called-for subscribers line and causing his bell to ring. When subscriber A releases ringing key 62, it closes circuit through the substation, relay 281 is again energized, opening contact 282-283, deenergizing relay 288 and allowing the said relays armatures to resume their normal positions. When subscriber B, in response to the call, removes his receiver from the hook and closes contact 73-72, an additional path for the flow of current, from battery 287, is established as follows: from the grounded side of the said battery, through the lower winding of relay 284, through winding 292 of relay 290, through contact 304-303, over the talk ing circuit at the exchange, to limb S of the line of subscriber B, through the substation, returning over limb P, over the talking circuit, through contact 300-302, through winding 291 of relay 290, through the upper winding of relay 284 to the active side of battery 2871 This flow of current causes the energization of relay 290, attracting its armatures to close contacts 294-295 and 296-297, contacts 293-294 and 295-296 being opened. The original flow of current, from battery 287 over the line of subscriber A, was from the grounded side of the said battery, over limb S, returning by way of limb P to the active side of the said battery.

The attraction of the armatures of relay 290 reverses the direction of this flow of current, the pathnow being traced from the grounded side of'battery 287, over limb P of the line, returning over limb S to the active side of the battery.

While the provision of means for reversing the direction of the flow of current in the calling subscribers line, upon the response of the called-for subscriber, is not essential to the operation of the system as shown, the feature is of value as rendering the system of the whole more flexible, being adapted to be used for various signaling urposes in connection with polarized electromagnets. An example of structures such as may be used in connection with the present system is shown in Fig. 5 of Patent No. 830,653 to Alfred H. Dyson, issued September 11, 1906.

When at the conclusion of the conversation, either subscriber depresses keys 60 and I 61 to ground the limbs of his line and replaces his receiver, the neutralizing ef'fect of its two windings upon the core of differentially-wound relay 284 is unbalanced; armature 285 is attracted to engage anvil 286, establishing a path for the flow of current from ground at the second selector switch, Fig. 5, through the winding of release relay 17 5, through contact 164-162, through contact 167-165-166, contact 285-286, then joining the flow from ground through relay 276, through contact 231-228, through the winding of release magnet 232 of the connector switch, Fig. 4 to battery 189, causing the energization of release magnet 232 and release relay 175 of the second selector switch, Fig. 5. Relay 276 of the battery control circuit, Fig. 5, continues energized under these conditions. The energizations of the release magnets of the second selector switch, first selector switch and the private switch are accomplished in the same manner as described in connection with the first complete circuit diagram. When'the releasing subscriber removes ground from v the two limbs of his line atthe substation, armature 285 of relay 284 (Fig. 5) disengages anvil 286 and opens circuit through release relay 175 of the second selector switch, Fig. 5, and

.release magnet 232 of the connector switch,

Fig. 4, causing theirdeenergizations. The deenergization of release magnet 232 causes the return of the connector switch, Fig. 4, to normal; the opening of contact 231-228, caused thereby, breaks the circuit through relay 276 of the battery control circuit, Fig. 5, denergizing it, arms 270, 273, 300 and 303 thereupon returning to normal.- The returns to normal of the second selector witch, first selector switch and the private switch are accomplished as described in connection with the first complete circuit diagram.

the circuit. of my invention for providing means whereby subscribers whose lines terminate in difierent exchanges may automatically interconnect their lines, two conductors only being required for a trunk circuit between exchanges, comprises Fig. 2, Fig. 6, Fig. 5 and Fig. 4 placed in the order named .120 A third complete diagram, illustrative of with Fig. 6 superposed upon Fig. 5 so that the left portion of Fig. 5 including contacts166,

170 and 173 is covered by Fig. 6. p and s are the two limbs of a trunk circuit; the apparatus in this diagram to their left being assumed to be in one exchange, and that to their' right in the second exchange. The method of operation of this circuit is similar to those 'already described tothe point at which Wipers 129, 133 and 136 of the first selector switch, Fig. 2', come to rest in engagement with contacts 130, 134 and 137 Impulses of. relay 309, each attraction and release causing an impulse of current to flow as follows: from ground at Fig. 6, through contact 313'312, through contact 348347, over limb p of the trunk line, through contact 142'143, through the winding of rimary relay 145 of the trunking second se ector switch, Fig. 6. The four attractions and releases of the armature of relay 145, caused by the above-mentioned impulses of current, cause four impulses of current to flow from ground at the second selector switch, Fig.6, through contact 150151, through contact 148-147, through the winding of primary magnet 153 to battery 149, causing four primary movements of shaft 168 and the movement of wipers 165 169 and 172 to positions adjacent to, but not engaging, levels of contacts, terminals of connector switches assigned to the four hundreds group of the third thousand. The calling subscriber now causes one impulse of current to flow from ground at the substation, over limb S of the line, through contact 138-136137, through contact 318319, throu h the winding of secondary trunk relay 31 to battery 321, causing the attraction and release of the armature of said relay and an impulse of current to flow from ground, through contact 313-314, through contact 351350, over limb s of the trunk line, through contact 204205, through the winding of sec ondary relay 207 to battery 149. The resulting attraction and release of the relays armature causes an impulse of current to,

flow from ground at Fig.6, through contact 210209, through the winding of circuitchanging switch magnet 154 to battery 149. causing the energization of the magnet and the attraction of its armatures. The closing of contact 150152 causes a flow of current from ground, through the said contact,

through the winding of secondary magnet 157 to battery 149. Wipers 165, 169 and 172 the busy move over the contacts of the before-mentioned levels, terminals of busy connector switches being grounded, as described in connection with the previous diagrams, and maintaining the circuit-changingv switch magnet energized. When the wipers reach contacts, terminals of an idle connector switch, circuit-changing switch magnet 154 is deenergized, opening circuit through secondary magnet 157 and preventing further movement of the wipers under the influence of the said magnet. At the same time, it moves arms 162, 142 and 204 into engagement with contact points 164, 144 and 206, respectively.

The impulses sent from ground by subscriber A, corresponding to the tens digit of the called subscribers number, cause five .energizations and deenergizations of rimary trunk relay 309, resulting in five impulse of current, sent by subscriber A from ground at the substation, over limb S of the line, passes through secondary trunk relay 317, over the previously traced path. The energization and deenergization of this relay causes an impulse of current to flow from ground, through contact313-314,.through contact 351--350, over limb 8 of the trunk line, through contact 204-206, contact 17 4 17 2173, contact 273-274, contact 305303, contact 2172 18, through the winding of relay 221 to battery 189. Relay 221 operates the connector switch, as previously described. The four impulses corresponding to the units digit of the called 'subscribers number, sent by subscriber A over limb P of the line, and a single impulse, following the four, sent over limb S, aretransmitted by relays 309 and 317 of Fig. 6 to relays 188 and 22 1 of the connector switch, Fig. 4, over the previously traced paths, causing wipers 236, 240 and 243'to engage terminals of the called subscribers line.

Should the line be busy, the connector switch is released and subscriber A receives signal from busy-back machine 263, as previously described.

Should the line be idle, the engagement of arm 228 with contact 231 causes a flow of current from ground at battery control circuit, Fig. 5, through relay 276, contact 231-228 and release magnet 232 to battery 189, the latter magnet not being operated 

